From e16b46605960bd071a3e26f316e0bb600ae91e37 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Thu, 21 Jul 2016 21:40:28 -0600 Subject: PCI: Allow additional bus numbers for hotplug bridges A user may hot add a switch requiring more than one bus to enumerate. This previously required a system reboot if BIOS did not sufficiently pad the bus resource, which they frequently don't do. Add a kernel parameter so a user can specify the minimum number of bus numbers to reserve for a hotplug bridge's subordinate buses so rebooting won't be necessary. The default is 1, which is equivalent to previous behavior. Signed-off-by: Keith Busch Signed-off-by: Bjorn Helgaas --- drivers/pci/probe.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'drivers/pci/probe.c') diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 8e3ef720997d..f680099c110d 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2076,6 +2076,15 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus) max = pci_scan_bridge(bus, dev, max, pass); } + /* + * Make sure a hotplug bridge has at least the minimum requested + * number of buses. + */ + if (bus->self && bus->self->is_hotplug_bridge && pci_hotplug_bus_size) { + if (max - bus->busn_res.start < pci_hotplug_bus_size - 1) + max = bus->busn_res.start + pci_hotplug_bus_size - 1; + } + /* * We've scanned the bus and so we know all about what's on * the other side of any bridges that may be on this bus plus -- cgit v1.2.3